Monoazo dispersion dyes for cellulose acetates - and polyamides, prepd from 2-amino 1,3,4-thiadiazole diazo components and 1,2,3,4-tetrahydroquinoline coupling components

Title dyes are of formula (I): (where R is H, lower alkyl, cycloalkyl, aryl, lower alkyl-sulphonyl or R6X, R6 is opt. substd lower alkyl, arylalkyl, cycloalkyl or aryl and X is O or S; R1 is H, halogen, lower alkyl, alkoxy, alkanoyl-amido, aroylamido, benzamido, alkyl benzamido, alkoxy-benzamido or alkyl sulphonamido; R2, R3 and R4 are H or lower alkyl and R5 is opt. substd lower alkyl), In pref. cpds R2 is 2-4C alkyl, R3 and R4 are hydrogen and R5 is lower alkyl or -YR7, in which Y is ethylene or propylene, and R7 is hydroxy, cyano, lower alkoxy, carbamoyl, lower alkanoyloxy or alknoylamido, or benzmido. Alternatively R1R2 and R3 are methyl, or H, R is phenyl, lower alkoxy or alkylthio and R4 is methyl or H. (I) are suitable for dyeing cellulose acetates and polyamides in strong scarlet to pink shades, showing excellent affinity and fastness to migration and light.